A Range Finder by Using a Rotary Cubic Mirror

The slit light scanning method is a conventional method of range finder. But according to this method, it is impossible to measure the three dimensional shape when the object is too large, because camera is fixed against the observation field. In this paper, we propose a new active range finder with a rotary cubic mirror to solve these problems. In this sensing system, slit light and view of camera are moved to the same direction simultaneously by using a rotary cubic mirror. This method is able to obtain the slit light image which dose not include distortion. On the other hand in the proposed sensing system, the image of slit is projected on near the center of the image plane all the time by moving the slit light and the view of camera simultaneously. The experiments were performed to demonstrate the efficacy of this sensor by using this system. As a result, the proposed method can measure the three dimensional position of the object and effectiveness was shown. becomes wide because view of camera is moved by revolving motor. And slit light moves with view of camera to same direction simultaneously, so image of slit is projected near the center of image plane all the time. But this system has some problems. It will become complex system composition because it uses two motors. And to operate the two motor a t the same time together, strict calibration is in need. We propose a new active range finder with simple system component, and no need a strict calibration to move slit light and view of camera simultaneously. This sensor uses swinging mirror that has a cubic shape. This mirror is located between CCD camera and slit light projector. The two units are opposite from each other. Thus, only swinging cubic mirror can realize to move slit light and view of camera simultaneously to the same direction, as a result, there is no need strict calibration. In this paper, we describe the principle of measurement, system component, calculation of 3D position, and results of experiment to verify the efficiency of this method.